1. Field of the Invention
The present invention relates to a pixel and an organic light emitting display using the same, and particularly a pixel and an organic light emitting display using the same capable of compensating for deterioration of an organic light emitting diode.
2. Description of Related Art
Recently, various flat panel display devices capable of reducing weight and volume, which are unfavorable in a cathode ray tube, have been developed. Flat panel display devices can include: liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs) and organic light emitting display (OLEDs).
Among the flat panel display devices, the OLED displays an image using an organic light emitting diode generating light by recombination of electrons and holes. Such an organic light emitting display has advantages in that it has a rapid response speed while being driven with low power consumption.
FIG. 1 is a circuit diagram showing a pixel of a conventional organic light emitting display disclosed in Korean Patent Registration No. 10-0815756.
Referring to FIG. 1, the pixel 4 of the conventional organic light emitting display includes an organic light emitting diode OLED, and a pixel circuit 2 coupled to a data line Dm and a scan line SN to control the organic light emitting diode OLED.
An anode electrode of the organic light emitting diode OLED is coupled to the pixel circuit 2, and a cathode electrode thereof is coupled to a second power supply ELVSS. Such an organic light emitting diode OLED generates light having a predetermined brightness corresponding to current supplied from the pixel circuit 2.
The pixel circuit 2 controls current amount supplied to the organic light emitting diode OLED corresponding to a data signal supplied to the data line Dm when a scan signal is supplied to the scan line Sn. To this end, the pixel circuit 2 includes a transistor M1, a transistor M2, and a storage capacitor Cst. The transistor M2 is coupled between a first power supply ELVDD and the organic light emitting diode OLED. The transistor M1 is coupled between the transistor M2, the data line Dm, and the scan line Sn. Also, the storage capacitor Cst is coupled between a gate electrode and a first electrode of the transistor M2.
A gate electrode of the transistor M1 is coupled to the scan line Sn, and a first electrode thereof is coupled to the data line Dm. A second electrode of the transistor M1 is coupled to one side terminal of the storage capacitor Cst. Herein, the first electrode is set to any one of a source electrode and a drain electrode, and the second electrode is set to the other electrode different from the first electrode. For example, if the first electrode is set to the source electrode, the second electrode is set to the drain electrode. When the scan signal is supplied from the scan line Sn, the transistor M1 coupled to the scan line Sn and the data line Dm is turned on to supply the data signal supplied from the data line Dm to the storage capacitor Cst. At this time, the storage capacitor Cst is charged with a voltage corresponding to the data signal.
The gate electrode of the transistor M2 is coupled to one side terminal of the storage capacitor Cst, and the first electrode thereof is coupled to the other side terminal of the storage capacitor and the first power supply EVLDD. A second electrode of the transistor M2 is coupled to the anode electrode of the organic light emitting diode OLED. Such a transistor M2 controls the amount of current flowing from the first power supply ELVDD to the second power supply ELVSS via the organic light emitting diode OLED corresponding to a voltage value stored in the storage capacitor Cst. The organic light emitting diode OLED then generates light corresponding to the current amount supplied from the transistor M2.
However, such a conventional organic light emitting display has a problem in that it becomes impossible to display an image having a desired brightness due to an efficiency change as a result of a deterioration of the organic light emitting diode OLED. In other words, as the organic light emitting diode deteriorates over time it is becomes impossible to display the image in the desired brightness. In essence, as the organic light emitting diode deteriorates, light having a low brightness is generated.